Growth of ordered Tantalum films and Integration into Quantum Circuits

We investigate the growth of tantalum on Si and sapphire to understand the limits of atomically-ordered superconducting qubit construction. On c-plane sapphire we observe (111)-oriented bcc Ta films with residual resistivity ratios exceeding 60 in 200 nm films. We present x-ray diffraction, low temperature transport, and transmission electron microscopy studies of these films and further demonstrate resonators with low-power quality factors exceeding 10⁶ at 10 mK, 2D and 3D transmon qubits with coherence times up to 400 us, and the production of bcc Ta airbridges.